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Background and Purpose: Middle cerebral artery steno-occlusive disease (MCAD) is not an uncommon cause of ischemic stroke in young Asians. Aside from atherosclerosis, the pathogenesis of MCAD include various nonatherosclerotic vasculopathies, most of which are yet to be defined. This study investigated the pathogenesis of symptomatic isolated MCAD in young Asian patients using high-resolution magnetic resonance imaging (HR-MRI) and mutation analysis of RNF213., Methods: Patients aged <60 years with stroke or transient ischemic attack caused by MCAD were prospectively enrolled. Patients with a confirmed diagnosis of moyamoya disease, dissection, and vasculitis; with significant steno-occlusion in cerebral arteries other than the MCA; or with high-risk cardioembolic source were excluded. Using high-resolution MRI, patients were classified into an atherosclerosis group and a nonatherosclerosis group., Results: Eighty-one patients were enrolled, 45 (56.6%) in the atherosclerosis and 36 (44.4%) in the nonatherosclerosis group. The nonatherosclerosis group was significantly younger (P=0.013), had a smaller number of vascular risk factors (P=0.001), showed a lower homocysteine level (P<0.001), thinner intima-media thickness (P=0.006), and had more frequent heterozygotes at RNF213 (P=0.045) than the atherosclerosis group. Diffusion-weighted image lesion pattern showed no significant differences in assumed stroke mechanisms between the 2 groups., Conclusions: Nonatherosclerotic pathogenesis are common in young Asians with symptomatic isolated MCAD. Clinical findings, high-resolution MRI features, and results of RNF213 mutation analysis suggest that moyamoya disease is responsible etiologically for a significant portion of nonatherosclerotic lesions. Symptomatic isolated MCAD may be an early manifestation of moyamoya disease in young Asian adults., (© 2016 American Heart Association, Inc.)

Background Conventional risk factors cannot explain the individual or ethnic difference in the location of cerebral atherosclerosis. Vascular geometry may play a role on this. Aim To investigate the association between the geometrical properties of the middle cerebral artery and intracranial atherosclerosis. Methods Stroke patients with either symptomatic middle cerebral artery or proximal internal carotid artery diseases were enrolled. The diameter, length, and tortuosity (arc-chord ratio, by percent) of the middle cerebral artery was compared between stroke patients and the age- and gender-matched healthy subjects. The geometrical property was also compared between the symptomatic middle cerebral artery and the normal-looking contralateral middle cerebral artery, and between the contralateral middle cerebral arteries in patients with symptomatic middle cerebral artery and proximal internal carotid artery diseases. Results One hundred seventy-seven patients (101 with middle cerebral artery disease and 76 with proximal internal carotid artery disease) were studied. Symptomatic middle cerebral artery was more tortuous (119·31 ± 16·95 vs. 112·98 ± 14·16; P = 0·009) than the contralateral middle cerebral artery. The contralateral middle cerebral artery of patients with symptomatic middle cerebral artery disease demonstrated a smaller proximal diameter ( P = 0·007) and a greater vascular tortuosity than the contralateral middle cerebral artery of patients with proximal internal carotid artery disease (112·01 ± 12·25 vs. 107·46 ± 9·35; P = 0·008) and corresponding middle cerebral artery of healthy control subjects (112·01 ± 12·25 vs. 108·73 ± 9·79; P = 0·04). Young age, female, small diameter, the absence of diabetes, and high tortuosity of the contralateral middle cerebral artery were independently associated with middle cerebral artery atherosclerotic disease. Conclusions High tortuosity and small diameter are related to middle cerebral artery atherosclerosis, probably by altering hemodynamics. Different degree of tortuosity may be one of the reasons for individual differences in location of cerebral atherosclerosis. [ABSTRACT FROM AUTHOR]

Background The location of plaque may be associated with the vascular geometry. Aim We aimed to examine the relationship between the geometry of middle cerebral artery and the plaque location detected by high-resolution magnetic resonance imaging. Methods Among patients with a single subcortical infarction without a significant middle cerebral artery stenosis on magnetic resonance angiography, those with a plaque detected from high-resolution magnetic resonance imaging were prospectively enrolled. The shape of middle cerebral artery was measured from the coronal view, and was classified as straight, U-shaped, inverted U-shaped, and S-shaped. The location of the plaque was divided into superior and inferior, and analyzed according to the shape of middle cerebral artery. Results Among the 40 patients, the shape of middle cerebral artery was straight in 7 (17·5%), U-shaped in 10 (15·0%), inverted U-shaped in 11 (27·5%), and S-shaped in 12 patients (30·0%). The superior plaque was more closely associated with straight (85·7%) or U-shaped middle cerebral arteries (90·0%), whereas inverted U-shaped (81·8%) and S-shaped middle cerebral arteries (75·0%) were more often associated with inferior plaque. The prevalence of symptomatic plaque was higher in superior than inferior plaques (70·0% vs. 25·0%, P = 0·004). Multivariate analysis showed that straight and U-shaped middle cerebral artery was the only significant factor associated with the superior plaque. Conclusion The shape of middle cerebral artery may be a factor determining the location of early atherosclerotic plaque. [ABSTRACT FROM AUTHOR]